how did so many unrelated languages around the world come to have essentially identical systems of communication?

Question

Such as very similar or near-identical vocabularies, phrases, greetings, yes/no/maybe, exclamations etc.

In: Culture

Answer 1

Because they are, in fact, related. For example, just about any language spoken in the Americas, Europe, parts of Asia and the Middle East are all part of the Indo-European family of languages, that all evolved from the same language thousands of years ago.